294 (#385) ############################################ TWISTING THEORIES AND PRACTICE Example: A 1/16's yarn is to be twisted into a 4/16's hosiery yarn. Find the single and fourfold twist. (1) 15° hosiery angle gives 8 turns per inch single; and (2) balanced twist gives 2 turns per inch for the folded yarn. The experimental yarn spinner should experiment with yarns in which the twofold twist much exceeds the single twist. Special twist effects—at comparatively little cost-are thus produced. The relative costs of producing the various types of single and twist yarns should also be worked out and graphed. Actual examples of the four types of twist yarns graphically illustrated in Fig. 86 are given in Fig. 87. In Fig. 88 a nomogram designed by Dr. Brodetsky, of the University of Leeds, is given, the use of which is so much in evidence that it need not here be described. All calculations relating to twist angles and turns per inch can be solved by merely placing a straight-edge correctly on this graph. It may be asked—Is there no variation in twist to be made for quality or for any other variable condition ? The answer is-Probably. But the foregoing par- ticulars are so satisfactory in the results they give that it will take a very clever spinner or cloth constructor to improve upon them within ordinary count limits.* It will be found that they act as a wonderful key to almost all twist problems; the few cases they do not cover being quite insignificant. Similarly the principles here enumerated so dominate everything else that they may be taken equally to apply to flyer, cap, ring or mule twisting. * For abnormally low and abnormally high counts there is probably a factor which has not yet been isolated nor taken into account: 295